I've used these with a couple brews now. I recommend taking a small sample out of your hot mash or whatever you're measuring, letting it cool, then putting a drop on the stick, rather than dipping into the hot solution. Dipping seems to grab too much liquid on the stick and the color then runs, possibly being less accurate.

The photo gives you a sense of what the colors really look like across the range. Far left= lime juice (pH ~3.5), far right = saturated NaHCO3 (pH ~9), in the middle is coffee brewed this morning to simulate some pH's actually in-range (coffee is around pH 5-6ish depending on strength)